In a digitally controlled printing system, a print media is directed through a series of components. The print media can be cut sheet or a continuous web. As the print media moves through the printing system, liquid, for example, ink, is applied to the print media by one or more lineheads. This is commonly referred to as jetting of the ink.
In commercial inkjet printing systems, the print media is physically transported through the printing system at a high rate of speed. For example, the print media can travel 650 to 1000 feet per minute. The lineheads in commercial inkjet printing systems typically include multiple printheads that jet ink onto the print media as the print media is being physically moved through the printing system. A reservoir containing ink or some other material is usually behind each nozzle plate in a linehead. The ink streams through the nozzles in the nozzle plates when the reservoirs are pressurized.
The printheads in each linehead in commercial printing systems typically jet only one color. Thus, there is a linehead for each colored ink when different colored inks are used to print content. For example, there are four lineheads in printing systems using cyan, magenta, yellow and black colored inks. The content is printed by jetting the colored inks sequentially, and each colored ink deposited on the print media is known as a color plane. The color planes need to be aligned, or registered with each other so that the overlapping ink colors produce a quality single image.
Color registration errors can be partitioned into different types. Examples of color registration errors include, but are not limited to, a color plane having a linear translation with respect to another color plane, a color plane being rotated with respect to another color plane, and a color plane being stretched, contracted, or both stretched and contracted with respect to another color plane.
There are several variables that contribute to the registration errors in color plane alignment including physical properties of the print media, conveyance of print media, ink application system, ink coverage, and drying of ink. Color registration errors are typically minimized by controlling these variables. However, controlling these variables can often restrict the range of desired print applications. For example, color plane to color plane registration errors will typically become larger than desired as paper weight for the print application is reduced, when ink coverage is increased and when the amount of ink coverage becomes more variable between printed documents. These limitations compromise the range of suitable applications for ink jet printing systems.